Submission #719488

#	Time	Username	Problem	Language	Result	Execution time	Memory
719488		vinnipuh01	Event Hopping (BOI22_events)	C++17	100 / 100	422 ms	58844 KiB

events

#include <iostream>
#include <bits/stdc++.h>
#include <cmath>
#include <algorithm>
#include <vector>
#include <deque>
#include <set>
#include <stack>
#include <string>
#include <map>
#include <queue>
#define int long long
#define sqrt sqrtl

using namespace std;

const long long oo = 1000000000000000000;

long long sum, ans = 0, mx = 0, mn = 1000000000, num, pos;


/*
    ViHHiPuh

   (( `'-""``""-'` ))
     )-__-_.._-__-(
   / --- (o _ o) --- \
   \ .-* ( .0. ) *-. /
   _'-. ,_ '=' _, .-'_
  / `;#'#'# - #'#'#;` \
 \_)) -----'#'----- ((_/
      # --------- #
  '# ------- ------ #'
  /..-'# ------- #'-.\
  _\...-\'# -- #'/-.../_
  ((____)- '#' -(____))


    cout << fixed << setprecision(6) << x;


    freopen ( "sum.in", "r", stdin )
*/

int n, q, x, y, l[ 100001 ], r[ 200001 ];
int mp[ 100001 ];
int t[ 800001 ];


struct Node {
	int mn, i;
	
	Node operator + ( Node a ) {
		Node c;
		if ( mn < a.mn )
			c.mn = mn, c.i = i;
		else
			c = a;
		return c;
	}
} tt[ 800001 ], an;

vector <pair<pair<int, int> , int> > vv;
vector <int> v[ 100001 ];
int pr[ 20 ][ 100001 ];
int tin[ 100001 ], tout[ 100001 ], tmr;
int used[ 100001 ];
vector <int> g;
map <int, int> mpp;

set <pair<int, int> > st;

void upd1( int v, int tl, int tr, int pos ) {
	if ( tl > pos || tr < pos )
		return;
	if ( tl == tr ) {
		if ( tt[ v ].mn > an.mn )
			tt[ v ] = an;
		return;
	}
	int mid = ( tl + tr ) / 2;
	upd1( v + v, tl, mid, pos );
	upd1( v + v + 1, mid + 1, tr, pos );
	tt[ v ] = tt[ v + v ] + tt[ v + v + 1 ];
}

void gett1( int v, int tl, int tr, int l, int r ) {
	if ( tl > r || tr < l )
		return;
	if ( tl >= l && tr <= r ) {
		an = an + tt[ v ];
		return;
	}
	int mid = ( tl + tr ) / 2;
	gett1( v + v, tl, mid, l, r ) ;
	gett1( v + v + 1, mid + 1, tr, l, r );
}

void build( int v, int tl, int tr ) {
	t[ v ] = oo;
	tt[ v ].mn = oo;
	if ( tl == tr )
		return; 
	int mid = ( tl + tr ) / 2;
	build( v + v, tl, mid );
	build( v + v + 1, mid + 1, tr );
}

void upd( int v, int tl, int tr, int pos, int x ) {
	if ( tl > pos || tr < pos )
		return;
	if ( tl == tr )  {
		t[ v ] = min( t[ v ], x );
		return;
	}
	int mid = ( tl + tr ) / 2;
	upd( v + v, tl, mid, pos, x );
	upd( v + v + 1, mid + 1, tr, pos, x );
	t[ v ] = min( t[ v + v ], t[ v + v + 1 ] );
}

void gett( int v, int tl, int tr, int l, int r ) {
	if ( tl > r || tr < l )
		return;
	if ( tl >= l && tr <= r ) {
		num = min( num, t[ v ] );
		return;
	}
	int mid = ( tl + tr ) / 2;
	gett( v + v, tl, mid, l, r );
	gett( v + v + 1, mid + 1, tr, l, r );
}

void dfs( int u, int pr ) {
	::pr[ 0 ][ u ] = pr;
	used[  u] = 1;
	tin[ u ] = ++tmr;
	for ( int i = 1; i < 20; i ++ )
		::pr[ i ][ u ] = ::pr[ i - 1 ][ ::pr[ i - 1 ][ u ] ];
	for ( auto to : v[ u ] ) {
		if ( to != pr )
			dfs( to, u );
	}
	tout[ u ] = tmr;
}

bool ok( int a, int b ) {
	return ( tin[ a ] <= tin[ b ] && tout[ a ] >= tout[ b ] );
}

int bin( int a, int b ) {
	for ( int i = 19; i >= 0; i -- ) {
		if ( r[ b ] < l[ pr[ i ][ a ] ] ) {
			a = pr[ i ][ a ];
			ans += ( 1 << i );
		}
	}
	return a;
}

main () {
    ios_base::sync_with_stdio(0);
    cin.tie(0); cout.tie(0);
	cin >> n >> q;
	build( 1, 1, n + n );
	for ( int i = 1; i <= n; i ++ ) {
		cin >> l[ i ] >> r[ i ];
		g.push_back( l[ i ] );
		g.push_back( r[ i ] );
	}
	sort( g.begin(), g.end() );
	for ( auto i : g ) {
		if ( !mpp[ i ] ) {
			mpp[ i ] = ++num;
		}
	}
	for ( int i = 1; i <= n; i ++ ) {
		l[ i ] = mpp[ l[ i ] ];
		r[ i ] = mpp[ r[ i ] ];
		upd( 1, 1, n + n, r[ i ], l[ i ] );
	}
	for ( int i = 1; i <= n; i ++ ) {
		vv.push_back( { make_pair( r[ i ], l[ i ] ), i } );	
	}
	sort( vv.begin(), vv.end() );
	for ( int i = 0; i < n; i ++ ) {
		mp[ vv[ i ].second ] = i + 1;
		l[ i + 1 ] = vv[ i ].first.second;
		r[ i + 1 ] = vv[ i ].first.first;
	}
	for ( int i = 1; i <= n; i ++ ) {
		an.mn = oo;
		gett1( 1, 1, n + n, l[ i ], r[ i ] );
		if ( an.mn < l[ i ] ) {
			v[ an.i ].push_back( i );
		}
		an = { l[ i ], i };
		upd1( 1, 1, n + n, r[ i ] );
	}
	for ( int i = 1; i <= n; i ++ ) {
		if ( !used[ i ] ) {
			dfs( i, i );
		}
	}
	int x, L, R;
	while ( q -- ) {
		cin >> x >> y;
		x = mp[ x ];
		y = mp[ y ];
		if ( x == y ) {
			cout << "0\n";
			continue;
		}
		if ( l[ y ] <= r[ x ] && r[ x ] <= r[ y ] ) {
			cout << "1\n";
			continue;
		}
		if ( y < x ) {
			cout << "impossible\n";
			continue;
		}
		ans = 2;
		y = bin( y, x );
		num = oo;
		gett( 1, 1, n + n, l[ y ], r[ y ] );
		if ( num <= r[ x ] )
			cout << ans << "\n";
		else
			cout << "impossible\n";
	}
}

Compilation message (stderr)

events.cpp:161:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
  161 | main () {
      | ^~~~
events.cpp: In function 'int main()':
events.cpp:205:9: warning: unused variable 'L' [-Wunused-variable]
  205 |  int x, L, R;
      |         ^
events.cpp:205:12: warning: unused variable 'R' [-Wunused-variable]
  205 |  int x, L, R;
      |            ^

• Subtask 1: 10 / 10
• Subtask 2: 10 / 10
• Subtask 3: 15 / 15
• Subtask 4: 15 / 15
• Subtask 5: 20 / 20
• Subtask 6: 30 / 30